package com.qbccn.gatewayservice.config;

import org.springframework.cloud.client.discovery.DiscoveryClient;
import org.springframework.cloud.gateway.discovery.DiscoveryClientRouteDefinitionLocator;
import org.springframework.cloud.gateway.discovery.DiscoveryLocatorProperties;
import org.springframework.cloud.gateway.route.RouteDefinitionLocator;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpMethod;
import org.springframework.http.HttpStatus;
import org.springframework.http.codec.ServerCodecConfigurer;
import org.springframework.http.codec.support.DefaultServerCodecConfigurer;
import org.springframework.http.server.reactive.ServerHttpRequest;
import org.springframework.http.server.reactive.ServerHttpResponse;
import org.springframework.web.cors.reactive.CorsUtils;
import org.springframework.web.server.ServerWebExchange;
import org.springframework.web.server.WebFilter;
import org.springframework.web.server.WebFilterChain;
import reactor.core.publisher.Mono;

@Configuration
public class GatewayServerConfig {
  // ----------------------------- 解决跨域 Begin -----------------------------

  private static final String ALL = "*";
  private static final String MAX_AGE = "3600L";

  @Bean
  public RouteDefinitionLocator discoveryClientRouteDefinitionLocator(
      DiscoveryClient discoveryClient, DiscoveryLocatorProperties properties) {
    return new DiscoveryClientRouteDefinitionLocator(discoveryClient, properties);
  }

  @Bean
  public ServerCodecConfigurer serverCodecConfigurer() {
    return new DefaultServerCodecConfigurer();
  }

  @Bean
  public WebFilter corsFilter() {
    return (ServerWebExchange ctx, WebFilterChain chain) -> {
      ServerHttpRequest request = ctx.getRequest();
      if (!CorsUtils.isCorsRequest(request)) {
        return chain.filter(ctx);
      }
      HttpHeaders requestHeaders = request.getHeaders();
      ServerHttpResponse response = ctx.getResponse();
      HttpMethod requestMethod = requestHeaders.getAccessControlRequestMethod();
      HttpHeaders headers = response.getHeaders();
      headers.add(HttpHeaders.ACCESS_CONTROL_ALLOW_ORIGIN, requestHeaders.getOrigin());
      headers.addAll(HttpHeaders.ACCESS_CONTROL_ALLOW_HEADERS,
          requestHeaders.getAccessControlRequestHeaders());
      if (requestMethod != null) {
        headers.add(HttpHeaders.ACCESS_CONTROL_ALLOW_METHODS, requestMethod.name());
      }
      headers.add(HttpHeaders.ACCESS_CONTROL_ALLOW_CREDENTIALS, "true");
      headers.add(HttpHeaders.ACCESS_CONTROL_EXPOSE_HEADERS, ALL);
      headers.add(HttpHeaders.ACCESS_CONTROL_MAX_AGE, MAX_AGE);
      if (request.getMethod() == HttpMethod.OPTIONS) {
        response.setStatusCode(HttpStatus.OK);
        return Mono.empty();
      }
      return chain.filter(ctx);
    };
  }

  // ----------------------------- 解决跨域 End -----------------------------
}
